<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="app">
        {{reversedText}}
    </div>
    <script src="https://unpkg.com/vue/dist/vue.min.js"></script>
    <script>
        var app = new Vue({
            el:'#app',
            data:{
                text:'123,456'
            },
            computed:{
                reversedText:function () {
                    return this.text.split(",").reverse().join(",");
                }
            }
        })
    </script>
</body>
</html>